Composite piston



E. E. ALLYNE.

COMPOSITE PISTON.

APPLICATION FILED AUG. 19, 1916.

1,329,820. Patented Feb. 20.

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v COMPOSITE PISTON.

APPLICATION FILEDAUG.19.\916.

Patented Feb. 3, 1920.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

EDMUND E. ALLYN E, OF CLEVELAND, OHIO, ASSIGNOR TO THE ALUMINUM CASTINGS COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

COMPOSITE PISTON.

Specification .of Letters Patent.

Patented Feb. 3, 1920.

Application filed August 19, 1916. Serial No. 115,887.

To all whom it may concern: I

Be it known that I, EDMUND E. ALLYNE a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and cient composite, skirted piston peculiarly adapted to meet the conditions which exist Within an internal combustion motor cylinder, including the stresses and strains imposed upon the piston, principally during the explosion stroke, and by the high heat generated at this time, which must be (a) efficiently and economically utilized in the translation of heat into mechanical energy and (b) that not translated into mechanical energy properly dissipated.

My present invention also contemplates an improvement in pistons of the general character disclosed in the Letters Patent 1,296,589 to Joseph H. Bamberg.

It further contemplates improvements on the construction of piston disclosed in Letters Patent of the United States No. 1,092,- 870, to Edward O. Spillman and Louis P. Mooers by simplifying the construction and manufacture of pistons of this patented type through making them in two or more parts, if desired of different materials, and of considerably lightening the construction as compared with the integral cast structure illustrated in the said patent.

Purely for the purposes of disclosure herein I have selected to illustrate and describe one construction of internal combustion motor, skirted piston embodying my improvements.

In the drawings, Figure 1 is a side elevation of a piston embodying my improvements.

Fig. 2 is a section on the line 22, Fig. 1.

Fig. 3 is a section on the line 33, Fig. 2.

Fig. 4 is a bottom or lower plan view.

Fig. 5 is a section on the line 55, Fig. 3.

Fig. 6 is a section on the line 66, Fig. 4c.

1 is the skirt, body or guide portion of the piston, which may be made of cast iron. bronze, a section of steel tubing, or any other suitable wear resisting material. It is formed with diametrically opposed apertures through it, 1, l", concentric with the axis of the wrist pin bosses, to perinitthe insertion and withdrawal of the wrist pin as desired and the circulation of lubricant. Preferably below said openingsl 1 said guide section 1 is formed with an inwardly extending boss 1, which may be screw-threaded, as shown in the drawings, for a. purpose later to be described. If made of a sectionof steel tubing, the guide portion 1 may be drawn so close in external diameter tothe internal diameter of the cylinder walls with which it is adapted to co-act and cooperate, that it should not be necessary to machine this section or guide portion of the piston, although it will be understood that if desired it may be machined or treated in any preferred mechanical manner.

3 indicates the head or top wall and connecting parts of the piston. It comprises, preferably, an end wall 3, an annular outer wall 3 preferably suitably grooved, as inclicated at 3", to receive suitable piston rings, inwardly extending wrist pin bosses 3 3*,

wrist pin bosses. Inwardly extending walls or ribs 3* also may be provided, if desired. The portions 3, 3, 3, 3 3 and 3 of the piston may be cast of a metallic alloy havin relatively low specific gravity. Their principal. functions are to'assist in translating the heat of the burning gases in the motor cylinder into mechanical energy, dissipate a part of that heat principally by conduction and radiation and-to carry the piston rings in such manner that they will co-act properly with the inner walls of the cylinder with which they are adapted to contact. The connection between the cast- .ing 3 and the skirt 1 is preferably made by securing the parts together at the cylindrical extension 3. For example, I have shown this extension 3 to be externally screwthreaded and fitted to the annular boss 1 on the guide section which is internally screw-threaded.

Preferably I cast the end wall 3, side wall 3, including section 3 bosses 3, 3 and webs 3 integrally and of an aluminum alloy, the principal component of which is the metal aluminum. I now prefer to make the head and connecting parts of the piston in accordand a cylindrical extension 3 below said ance with the improved process of said Joseph H. Bamberg set forth and described in his aforesaid Letters Patent, whereby the fit the inner walls of the motor cylinder,-

whereas the head 3 may be given a considerable amount of clearance between its outer wall 3* and the inner wall of the cylinder, to allow for all necessary expansion of the head due to the high temperatures to which it is subjected. The heat transmitted to the head which is not translated into mechanical energy is transferred downwardly by the side walls 3, webs 3, Wrist pin bosses 3, 3 and extension 3, and much of it is dissipated by radiation, so that the skirt 1 is kept relatively cool and may be readily lubricated to provide and maintain the proper working relationship between it and the inner wall of the motor cylinder. The fit between the skirt and the inner wall of the cylinder, as before indicated, may be a snug sliding fit, and the area of the skirt which co-acts with the inner wall of the motor cylinder is such as to insure against slapping or rapping of the piston against the inner wall of the cylinder. In fact the objectionable so-called piston slap, incident to the operation of nu- .merous types of pistons for use in internal combustion motors, is eliminated by the use of a piston constructed in accordance with my invention. Furthermore, a piston embodying my improvements herein described practically eliminates so-called oil pumping or transfer of an undue amount of oil or lubricant from the crank case to the upper end .of the piston, resulting in undesirable smoking and undue and troublesome carbonization, among other things.

To provide against straining, distorting or bending the relatively thin skirt or guide section 1, in operation of the piston, the side walls 3 of the casting 3 may carry downwardly extending lugs 3*, each of which projects below the upper free, adjacent end of the guide section 1 and serves as an abutment to limit the inward movement of the upper end of said guide section relative to the casting 3.

lVhere the guide section 1 carries an inwardly extending screw-threaded boss, such as 1, which cooperates with an externally screw-threaded extension 3 to connect the parts of the piston formed of different materials together, this connection and fit may be advantageously made by heating the guide section 1 about the boss 1 so as to expand. the same .and making 'a tight, screwthreaded fit with the portion 3 when thus or readily from said head to the skirt.

expanded, so that upon cooling a substantial shrink fit between the parts will be obtained.

Due to the fact that the sleeve or skirt is maintained relatively cool under all normal working conditions, the possibilities of scoring of the inner walls of the cylinder are practically eliminated.

The upper end of the skirt 1 is separated from the head 3 by an air gap. In the drawings, purely for the purpose of illustration, this air gap is shown relatively wide. The presence-of this air gap or air space between the upper edge of the skirt or body section 1 and the adjacent edge of the piston head, insures that the heat absorbed by the piston head principally will be transmitted inwardly and downwardly so that such por tion of it as does reach the skirt or body by conduction will do so near the lower end of the skirt and will not be sufficient in amount to cause the necessary expansion of the skirt which heat will not be transmitted efliciently It will be understood that this relationship might be that even of a poor mechanical fit or joint which would be a poor conductor of heat as compared with the metal of the side walls 3 so that the heat to be dissipated by the part 3 would largely be radiated rather than transferred across the gap between the upper end of the skirt 1 and side walls 3* or through the joint connecting the lug 1 and extension 3.

It will be noted that my composite piston may be made relatively light in weight, which is of material advantage in assisting in reducing the weight of the reciprocating parts of the motor.

Pistons of my improved construction will be found to operate comparatively noiselessly, smoothly and efiiciently.

Where the cast portion of my composite piston, above described, is made in accordance with said invention of Joseph H. Bamberg, set forth and described in his aforesaid Letters Patent of the United States, the casting will be suitably chilled so that the structure will be relatively fine grained and non-porous and the eutectic will substantially surround the excess substance in the structure.

Under certain circumstances it may be advantageous to use a sleeve 1 constructed concentric with said head by said abuttallic aluminum alloy of which the bodyof the piston is made. For example, the skirt 1 might to advantage be made of bronze, particularly might this be true where the cylinder wall against which the piston was to operate were made of metallic alloy of aluminum.

Instead of making the connection between the extension 3 and skirt by means of screw threads, it may be made by riveting'or by both screw threading and riveting together the parts.

To those skilled in the art many modifications of and widely differing embodiments and applications of my invention will suggest themselves, without departing from the spirit and scope thereof. My disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

Vhat I claim is:

1. A composite piston for an internal combustion motor having a head, wrist pin bosses and an extension below said wrist pin bosses cast integrally of a metallic alloy having a relatively low specific gravity, said casting having the structure which results from quickly chilling or setting the inner and outer walls of said casting against chilling metallic surfaces and which structure furthermore is substantially free from cavities due to crystallization shrinkage, and a tubular guide section of wear resisting material, the outer Walls of which are adapted to fitsnugly within the cylinder walls of an internal combustion motor, there being a relatively small air gap between the upper edge of said guide section and the adjacent edge of said head and said wrist pin bosses and extension being extended into said guide section and said extension being secured to said guide section by a connection which is a relatively poor conductor of heat.

*2. A composite piston for an internal combustion motor having a head, abutments, wrist pin bosses therebelow and an extension below said wrist pin bosses, all cast integrally of a metallic alloy having a relatively low specific gravity, said casting having the structure which results from quickly chilling or setting the inner and outer walls of said casting against chilling metallic surfaces and which structure furthermore is substantially free from cavities due to crystallization shrinkage, a tubular iron guide section into which said wrist pin bosses and extension project, there being a relatively small air gap between the upper edge of said guide section and the adjacent edge of said head, said guide section being secured beneath said wrist pin bosses to said extension on the casting and the upper free end of said guide section being maintained ments.

3. A composite piston for an internal combustion motor, comprising a head, wrist pin bosses and an extension below said boss-es cast of a metallic alloy having a relatively low specific gravity, the head having its side wall formed with grooves to receive packing rings, and a guide section of wear resisting metal into which said wrist pin bosses and extension project, there being a relatively small air gap between the upper end of said guide section and the adjacent edge of said head, and said extension being secured to said guide section below said bosses by a connection which is a relatively poor conductor of heat, said head carrying abutting walls for engagement with the inner will of said guide section at its, upper free end to maintain the axial alinement of said head and guide section.

4. A composite piston for an internal combustion motor, comprising a head, wrist pin bosses and a ring-like extension below said bosses cast of a metallic alloy having a relatively low specific gravity, the head having its side wall formed with grooves to recelve packing rings, and a guide section of wear resisting metal into which said wrist pin bosses and extension project, there being a relatively small air gap between the upper end of said guide section and the adjacent edge of said head, and said extension being secured to said guide section below said bosses by a connection which is a relatively poor conductor of heat, said head carrying abutting walls for engagement with the inner wall of said guide section at its upper free end to maintain the axial alinement of said head and guide section.

5. A composite piston for an internal combustion motor, comprising a head, wrist pin bosses and a ring-like extension below said bosses cast of a metallic alloy having a relatively'low specific gravity, and a guide section of bronze into which said wrist pin bosses and extension project, there being a relatively small air gap between the upper end of said guide section and the adjacent edge of said head, and said extension being secured to said guide section below said bosses by a connection which is a relatively poor conductor of heat, said head carrying abutting walls for engagement with the inner wall of said guide section at its upper free end to maintain the axial alinement of said head and guide section.

v6. A composite piston for an internal combustion motor, comprising a head, wrist pin bosses and a ring-like extension below said bosses cast of a metallic alloy having a relatively low specific gravity and a high coelficient of thermal expansion in comparison with iron, and a guide section of wearresisting metal having a low coeflicient of thermal expansion in comparison with the said metallic alloy, said guide section having a screw threaded connection with the said extension formed by external threads on the extension and complementary internal threads on the middle part of the guide section.

7 A piston for an internal combustion motor having a head,.wrist pin bosses and. an extension below said bosses. cast inte- 'grally of an alloy having a low specific gravity in comparison with iron, and a separate tubular guide section of wear-resisting metal connected to the said extension and extending upwardly and downwardly from its connection, said guide section having a relatively thin wall with an inturned annular flange at its lower end.

8. A piston for an mternal combustion motor having a head, wrist pin bosses, abutments above said bosses and an extension below said bosses cast integrally of an alloy having a low specific gravity in comparison with iron, and a separate tubular guide section of wear-resisting metal connected to the said extension and extending upwardly and downwardly from its connection, said guide section having a relatively thin wall which at its upper end has its inner surface in engagement with the said abutments.

9. A pistonfor an internal combustion motor, comprising a head, wrist pin bosses,

an extension below said wrist pin bosses,

a relatively small air gap, said head being provided with abutments which engage the inner wall of said guide section at its upper free end to maintain the axial alinement of said head and guide section,

10. A piston for an internal combustion motor, comprising a head, wrist pin bosses, an extension below said wrist pin bosses, and a tubular guide section connected intermediate its ends and about its inner periphery to said extension and having its upper edge spaced from said head by a relatively small air gap, said head being provided with abutments which engage the in- I ner wall of said guide section at its upper free end to maintain the axial alinement of said head and guide section.

In testimony whereof I aflix my signature in the presence of two witnesses.

EDMUND E. ALLY'NE.

Witnesses J. E. PEcK, J. F. MoOAsHEN. 

